JP3182416B2 - Drive control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a drive control device, more specifically, a drive device for driving a driven body by a motor, in which the driven body is accurately stopped at a target position. It relates to a control device.

[Prior art] A driving device for driving a driven body by a motor has been widely used in electronic devices in various fields.
For example, a camera is often used in an automatic focusing device that controls a photographic lens to move to a focusing target position. In this type of automatic focusing apparatus, in the technical means proposed by the present applicant in Japanese Patent Application Laid-Open No. 63-153526, the optimum deceleration curve of the taking lens is stored,
The drive speed and the deceleration curve are compared, and the lens is decelerated (combination of ON, OFF, and short brake) along the curve (hereinafter, referred to as curve control). Further, in the curve control, an automatic focusing device that changes the on-time of a motor in accordance with the moving speed of a taking lens and thereby quickly stops the taking lens at a target position is disclosed in JP-A-1-88412. Have been. Furthermore, two PI (photo interrupter) units are provided, and one PI output is provided when the distance is far from the target position, and two PI outputs are provided when the position is close to the target position. A drive control device which improves the above is proposed by the present applicant in Japanese Patent Application No. 2-40723.

[Problems to be Solved by the Invention] By the way, in such a lens drive control device,
One method for increasing the driving speed of the taking lens is to increase the voltage applied to the motor. However, if the applied voltage is simply increased, there is no problem regarding the off or brake operation in the above control, but there is a problem in the controllability at the time of on. That is, when the voltage is high, the acceleration is higher than when the voltage is low, so that the driving speed of the motor becomes too fast, and it is difficult to control along the deceleration curve.

In particular, when performing boot from a few pulses before the target stop position, the voltage applied to the motor is high, as shown in FIG. 12A, the driving voltage 5V (straight across from time t ₁ to the time width t _a after starting the motor by applying a l _21), even when braked at the rising time t ₂ of the PI output signal, since already the speed is too out, it can sometimes cause past the target position P _1. In this case, the motor must be further driven in the reverse direction, resulting in a problem such as hunting of the photographing lens near the target position. On the other hand, if the voltage is low, as shown in FIG.
_After the drive voltage of 2.5 V (straight line l ₂₂ ) is applied from ₃ to the time width t _b to start the motor, the PI output signal rise time point t ₄
In by multiplying the brakes, the motor is relatively so low speed, can be stopped without passing over the target position P _2.
Note that at low speed since the period towards the l ₂₄ from PI output signal waveform l ₂₃ is long. Therefore, although the controllability of driving several pulses is improved, the response at the time of starting the motor is delayed due to the low voltage applied to the motor, and it takes time to start rotating, and as a result, focusing cannot be performed quickly. become.

Accordingly, an object of the present invention is to provide a drive control device that solves the above-described problems, shortens the drive time when driving a driven body (photographing lens) to a target position, and enables highly accurate control. To be.

[Means for Solving the Problems] A drive control device according to the present invention is based on a motor 1 for driving a driven body to a target position in FIG.
Speed detecting means 2 for detecting the moving speed of the driven body
To stop the driven body at the target position,
A first storage means for storing an optimal deceleration curve set in accordance with the movement amount to the target position; and a calculation for detecting the movement amount of the driven body and calculating the movement amount to the target position. Means 3 for controlling the state of energization of the motor while comparing the moving speed of the driven body with the deceleration curve based on the movement amount to the target position calculated by the calculating means; The second storage means 7 for storing the motor drive voltage data set according to the movement amount to the target position, and the movement amount to the target position calculated by the calculation means and the second storage means. And a voltage control means for lowering the effective voltage applied to the motor based on the stored voltage data.

[Operation] In this drive control device, the output of the movement amount calculation means 3 to the target position and the motor drive voltage data from the second storage means 7 corresponding to the output are used to determine the target position such as the in-focus position. Up to a predetermined pulse before the position, the effective voltage applied to the motor 1 is increased by the voltage control means 5. During a period from a predetermined pulse before the target position to the target position, the motor 1 is driven while performing voltage control and speed control. That is,
Regarding the voltage control, the drive voltage data of the motor 1
Is stored in the storage means 7, the voltage control means 5 uses the output of the movement amount calculation means 3 to the target position and the corresponding voltage signal which is the output of the second storage means 7. Lower. As for the speed control, since the optimum deceleration curve is stored in the first storage means 6, the signal of the moving speed output from the speed detection means 2 and the deceleration curve corresponding thereto are stored. First
Speed control is performed based on the signal of the deceleration curve output from the storage means 6 of FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings. In the following embodiments, an example in which the drive control device according to the present invention is applied to lens driving in an automatic focusing device mechanism of a camera will be described. First, the first embodiment will be described below with reference to FIGS. .

FIG. 2 schematically shows the structure of an automatic focusing device for a camera. In the figure, the CPU 13 in the camera body 10
Then, when the distance information to the subject 12 measured by the distance measuring unit 14 is transmitted by triangulation, the CPU 13 determines the moving amount of the photographing lens 11 from the distance information, turns on the motor 1, and turns the motor 1 on. Start moving. The moving speed and moving amount of the photographing lens 11 are fed back to the CPU 13 by an encoder 15 including a photo interrupter or the like.

As shown in FIG. 3 (A), the encoder 15 is provided with a slit 17 of a rotating member which rotates with the driving of the motor 1.
And two PIs arranged across the passage of this slit 17
It consists of 18,19. And the above slit 17
In response to the rotation of the first, as shown in FIG.
PI output signals 20 and 21 having different phases are output from the PI 18 and the second PI 19, respectively.

FIG. 4 shows a motor 1 for driving the taking lens to a focusing position.
In the circuit diagram of the drive voltage control circuit, the digital data voltage signal from the CPU 13 is D / A converted by the D / A converter 22 and the voltage applied to the motor bridge circuit 24 is controlled by the transistor 23. The motor bridge circuit 24 has two
It is composed of PNP transistors Tr1 and Tr3 and two NPN transistors Tr2 and Tr4. The D / A converter 22 becomes unnecessary in the duty control described later.

For the operation of the motor 1, as shown in Table 1 below, "L" level input signals Q _1, by the "H" level Q _4, turning on the transistor Tr1, Tr4, also the input signal Q Set transistor ₂ to “L” level and Q ₃ to “H” level to set transistor T
By turning off r2 and Tr3, the motor rotates forward and
The Q ₁ "H" level, Q ₄ "L" level, "H" level input signal Q _2, is reversed by the the Q ₃ "L" level.

If braking by the "H" level of the input signal Q ₁ to Q _4, turning on the transistor Tr2, Tr4, Tr
1. Turn off Tr3 and short-circuit both ends of motor 1. Also, when turning off the input signal Q _1, Q ₃ to the "H" level, by setting respectively the input signal Q _2, Q ₄ to the "L" level, the motor 1 as all the transistors Tr1~Tr4 off Do not energize.

FIG. 5 is a graph showing a full speed region where speed control is not required and a control region where deceleration control is performed based on deceleration curve data.
5 is a timing chart of a PI output signal, a motor control signal, and a motor drive voltage. In the full speed range, the motor drive voltage is set to 5V because fast drive is required. On the other hand, in the control region, the motor drive voltage is reduced to 3.75, 2.5, 1.25 V in accordance with the falling amount of the PI output signal in accordance with the amount of movement to the target position. Thus, when the lens is driven while controlling the curve in the control area, the brake is applied too much in the vicinity of the target position, so that the target speed is not greatly exceeded even when the motor 1 is turned on and accelerated. can do.

Next, the control operation of the photographing lens drive in the CPU 13 will be described with reference to the flowchart shown in FIG.

When this program is started by operating a release switch or the like, first, the CPU 13 outputs a distance measurement command of the distance measurement unit 14 to perform AF distance measurement. Then, when receiving the distance measurement data from the distance measurement unit 14, the lens target position is converted into the number of encoder pulses (step S1). Then, after setting the motor drive voltage to 5V (see linear l ₄ of the FIG. 5) (step S2), and supplied to the motor 1 (step S3). After driving the motor, it is checked whether or not the photographing lens position is within a control range within a predetermined range from the target position (step S4), and the motor 1 is continuously driven at a voltage of 5 V until the photographing lens enters the control range. And when the taking lens reaches within the control range,
Proceeding to step S5, the motor drive voltage is set as follows. In other words, if the taking lens is two pulses before the target position
1.25 V (see the straight line l _{1 in} FIG. 5 above), 2.5 V (see the straight line l _{2 in} FIG. 5) three pulses before, and 3.75 V before the three pulses (see the straight line l _{3 in} FIG. 5). Refer to). Thus, the point of the present invention is that when the taking lens enters a control range within a predetermined range from the target position, the motor drive voltage is set according to the amount of movement to the target position. Is the second storage means (first
(See the figure). Then, it is determined whether or not the photographing lens has reached one pulse before the target position (step S6).
If it has not yet reached one pulse before the target position, the moving speed and the position of the taking lens are stored in the first storage unit 6.
Compared with the deceleration curve data stored in FIG. 1 (see FIG. 1), the deceleration curve control is performed until one pulse is reached. When the pulse reaches one pulse before, the short brake is applied to the motor 1 (step S8), and the control operation for driving the photographing lens is ended.

The above is the description of the first embodiment. In the first embodiment, as shown in FIG. 5, the driving range of the photographing lens is roughly divided into a full speed region and a control region. In the full speed region, the driving voltage applied to the motor 1 is set to 5 V, and In the control area, 3.75V, 2.5V, 1.2V depending on the amount of movement to the target position such as the focal point
Each was set to 5V. However, even in the control area, when the distance is far from the target position, there is little problem even if the acceleration at the time of turning on the motor in the curve control is large, but it is necessary to set the drive voltage so that the closer to the target position, the lower the acceleration can be.

An example of continuously changing the drive voltage applied to the motor 1 when the taking lens enters the control range will be described below with reference to FIGS. 7A and 7B as a modification of the first embodiment. If the curve is a curve as shown in Figure 7A, the drive voltage applied to the motor 1, as shown in Figure 7B, a high constant voltage shown by the straight line l ₅ in full speed region,
In the control region, as shown by a straight line ₁₆ , the voltage is changed continuously according to the amount of movement to the target position. This makes it possible to reduce the motor drive time in the control area.

FIGS. 8, 9A and 9B are a timing chart and a characteristic diagram of a drive control device according to a second embodiment of the present invention. This second
The difference between this embodiment and the first embodiment is that the motor 1
In the first embodiment, the voltage value is changed to, for example, 5V, 3.75V, 2.5V, 1.25V in order to change the effective voltage applied to the power supply, whereas in the second embodiment, the voltage value is changed. For example, the voltage is kept constant at 5 V, and the application time is changed.

In Figure 8, when starting from a few pulses before the target position, the drive voltage at the time of starting to be applied to the motor 1, temporarily as shown in the straight line l ₇ high, for example in the 5V, the rise of the motor At the same time, the time t _M for temporarily increasing the voltage in accordance with the amount of movement to the target position and the voltage value are stored in the second storage means 7 (see FIG. 1). Then, when the time t _M for temporarily increasing the drive voltage elapses, a normal drive voltage, for example, 2.5 V is applied to the motor 1 as shown by a straight line ₁₈ . This will be described with reference to FIGS. 9A and 9B.

That is, when performing curve control as shown in Figure 9A, the full speed region is the same as the first embodiment as shown in the straight line l ₉ of FIG. 9B. However, upon entering the control area, start from place away from the target position, as indicated by the straight line l ₁₀ of FIG. 9B, since the target speed is high, the time t _M for temporarily increasing the drive voltage long By taking this, the target speed is set in a short time, and starting from a position close to the target position decreases the target speed, so the time t _M for temporarily increasing the drive voltage is gradually shortened and the target speed is not exceeded The time t _M is set such that the rise time of the motor is shortened.

10A, 10B and 11 are characteristic diagrams of a drive control device according to a third embodiment of the present invention. In the first and second embodiments, the control is performed by changing the effective voltage applied to the motor 1, that is, the drive energy voltage value or the application time. In the third embodiment, the rectangular wave applied to the motor 1 is controlled. The control is performed by changing the duty ratio of the signal and thereby changing the driving torque. Such a square wave signal is
Specifically, it can be realized by repeating the on / off control of the motor 1 or repeating the on / off switching of the motor drive power supply. When performing curve control as shown in FIG. 10A, in the full speed region, the straight line l _{11 in} FIG. 10B is used.
At higher duty ratio as shown in, thus the high driving torque performs motor driving in, but with the movement amount to the target position as shown in the straight line l ₁₂ enters the control area gradually decreasing the duty ratio of the rectangular wave signal I am trying to do it.

Generally, the duty ratio is a ratio of the on-time Wa to one cycle Wb of the rectangular wave signal as shown in FIG. Is represented by The duty frequency is a reciprocal of the duty ratio and is an element related to the motor torque. That is, when the duty frequency is high, the torque decreases, and when the duty frequency is low, the torque increases. Therefore, the second storage means 7 shown in FIG. 1 stores information on the duty ratio and the duty frequency corresponding to the movement amount from the target position.

As described in detail in each of the above embodiments, the release time lag can be significantly reduced in driving the AF motor.
In each embodiment, the present invention has been described as an example in which the present invention is applied to an automatic focusing mechanism of a camera. However, it is needless to say that the present invention can also be applied to film winding. Furthermore, it is needless to say that the present invention is not limited to a camera, but can be widely applied to control of a driving device that drives a driven body by a motor.

[Effects of the Invention] As described above, according to the present invention, the amount of movement to the target position, that is, information such as voltage data according to the number of remaining pulses is stored in the storage means, and as the position approaches the target position. Since the effective voltage applied to the motor is reduced based on this information, the driving time for driving the driven body to the target position can be shortened, and highly accurate control can be performed. The effect is exhibited.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a drive control device according to the present invention, FIG. 2 is a schematic block configuration diagram of an automatic focusing device for a camera, and FIG. 3 (A) is a configuration of an encoder in FIG. FIG. 3 (B) is a timing chart of a PI output signal output from the photointerrupter in FIG. 3 (A), and FIG. 4 is a drive of a motor for moving a photographing lens to a target position. FIG. 5 is a timing chart of the PI output signal, the motor control signal, and the motor drive voltage in the first embodiment. FIG. 6 is a flowchart of the lens drive control of the CPU in FIG. FIG. 7A is a characteristic diagram showing a process of controlling the curve of the photographing lens by a moving amount and a moving speed, and FIG. 7B is a driving diagram applied to a motor in order to realize the curve control shown in FIG. 7A. Characteristic diagram of voltage, FIG. 8 is a timing chart of a drive control device according to a second embodiment of the present invention, and FIG. 9A is a characteristic diagram showing a process of controlling the curve of the taking lens by a moving amount and a moving speed. FIG. 9A is a characteristic diagram showing a time when a drive voltage applied to a motor is temporarily increased to a high voltage in order to realize the curve control shown in FIG. 9A. FIG. 10B is a characteristic diagram expressed in terms of the amount and the moving speed. FIG. 10B shows the drive voltage applied to the motor to realize the curve control shown in FIG. 10A in the drive control device according to the third embodiment of the present invention. Characteristic diagram of duty ratio, FIG. 11 is a characteristic diagram illustrating the duty ratio shown in FIG. 10B, and FIGS. 12A and 12B are cases in which a conventional drive control device is started several pulses before a target position. 6 is a timing chart of FIG. DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Speed detection means 3 ... Moving amount calculation means to a target position 4 ... Control means 5 ... Voltage control means 6 ... First storage means 7 ... Second storage means

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Claims (3)

(57) [Claims] A motor for driving the driven body to a target position; speed detecting means for detecting a moving speed of the driven body; and a target position for stopping the driven body at the target position. First storage means for storing an optimal deceleration curve set according to the movement amount up to, and calculation means for detecting the movement amount of the driven body and calculating the movement amount to the target position; In a region where the movement amount to the target position calculated by the calculation means is equal to or less than a predetermined value, the energized state of the motor is determined by energizing and de-energizing while comparing the moving speed of the driven body with the deceleration curve. Control means for stopping the driven body at the target position by switching, second storage means for storing motor drive voltage data set in accordance with the amount of movement to the target position; Travel and up A voltage control unit that reduces an effective voltage applied to the motor when the motor is energized, based on the voltage data stored in the second storage unit; and , The second
Drive voltage control means for applying a voltage higher than the effective voltage based on the voltage data stored in the storage means for a predetermined time according to the amount of movement to the target position. apparatus. 2. A duty ratio or a duty frequency set according to a movement amount to a target position is stored in said second storage means, and said voltage control means is calculated by said calculation means. The drive control device according to claim 1, wherein an effective voltage applied to the motor is reduced based on a movement amount to a target position and a duty ratio or a duty frequency stored in the storage unit. 3. The drive control device according to claim 1, wherein the driven body is a photographic lens of a camera.